EFFECTS OF SPERMINE ON THE RIBONUCLEOPROTEIN PARTICLES 245 



TABLE IV 



Binding of Radioactive Spermine to RNP Particles, and 

 THE Effect of Mg + + on this Binding 



Incubation conditions are given in the text. 



Exp. 

 No. 



Additions 



* When pellet was treated with 5% TCA, then re-spun, and pellet recounted, 

 0002 /timoles radioactive spermine remained bound. 



t When pellet was treated with 5% TCA, then re-spun, and pellet recounted, 

 o-ooiS ^moles radioactive spermine remained bound. 



to replace the Mg + + from the particles, and since the Mg + + seems to be 

 one of the principal instrumentalities in stabilizing these particles (cf. ref. 

 in [7]), it should follow that spermine also helps to bind the RNA to the 

 protein of the particles, and as Tables II and III indicate, it seems to do 

 so. 



Since we were doubly fortunate to be in New York City and knew of 

 certain experiments performed by Dr. Waelsch and his associates, and 

 were also friends of Dr. Waelsch and his associates, we were able to test 

 the above possibility by obtaining radioactive spermine from them. The 

 results are shown in Tables IV and V and Fig. i. Table IV shows, indeed, 

 that spermine is bound to the particles, while Table V shows that by far 

 the greatest part of the bound spermine cannot be washed off the particles 

 by further water incubation of the particles. Previously [7], we had found 



